DE102018218475B4 - Tracking system and optical measuring system for determining at least one spatial position and orientation of at least one measurement object - Google Patents

Abstract

Optical measuring system (140) comprising at least one tracking system (110) for determining at least one spatial position and orientation of at least one 3D measuring device (114), wherein the optical measuring system (140) comprises at least one 3D measuring device (114), the tracking system (110) comprises at least three cameras (116), the cameras (116) each being arranged at different spatial positions, the cameras (116) each having at least two color subsystems (128), the color subsystems (128) each have at least one bandpass filter, the bandpass filters of the color subsystems (128) of the respective camera (116) each having different transmission ranges, the tracking system (110) having at least one evaluation unit (136) which is set up to measure the measurement signals of the color evaluate subsystems (128) in parallel and to determine the position and orientation of the measuring device (114), and wherein the evaluation unit (136) is set up i st, in the areas in which the measurement volumes of the color subsystems (128) overlap, to consolidate measurement results using linear combinations, the 3D measurement device (114) being set up to determine 3D coordinates of an object to be measured, the 3D Measuring device (114) has at least one lighting device which is set up to generate a plurality of markers (142) on a surface of the 3D measuring device (114), with at least two of the markers (142) having different wavelengths, with the wavelengths each in a passband of one of the bandpass filters, wherein a brightness and/or size of the markers (142) can be adapted to a measuring field of the respective color subsystem (128).

Description

field of invention

The invention relates to an optical measurement system with a tracking system for determining at least one spatial position and orientation of at least one measurement object. The present invention relates in particular to the field of coordinate metrology for measuring large-volume components.

State of the art

In the field of measuring large-volume components, the component is usually scanned using a hand-held or robot-controlled scanner or probe, and a position and alignment of the scanner or probe is determined using an optical or mechanical tracker. Optical trackers from the company ZEISS are known, for example, in particular the optical trackers T-TRACK CS+ and T-TRACK LV.

Also known are measurement methods in which a component is scanned with a measuring head of a sensor and the position and alignment of the measuring head in a measuring volume is carried out by means of a distance measuring device and an additional angle measuring device. Devices of this type permit a high degree of accuracy, but the production of such devices with the desired high degree of accuracy is complex and leads to high costs.

US 2014/0028 861 A1 describes imaging systems and methods for object recognition in which a contrast between object and non-object surfaces is enhanced. DE 10 2010 028 904 A1 relates to a movement analysis and/or tracking system of moving or moving objects, which are provided with actively or passively radiating marker elements that radiate in a defined color and with a rounded or elliptical geometry, at least comprising: - at least one camera for recording the Movements of the object or objects, which are continuously stored as digital color images by means of at least one color image recorder; - A first transformer unit, which continuously converts the digitally stored color images into RGB images of the so-called RGB color space, so that there are three color intensities (RGB) for each color point; - A gray image generation unit, which accepts the maximum of the three color intensities as a gray value for each color pixel and continuously stores it as a monochrome gray image corresponding to the RGB images; - a localization unit which compares each gray value with a defined threshold value and stores gray values lying above the threshold value as a member of a pixel cloud representing a potential marker element; - A measuring unit, which measures the geometry of each pixel cloud in the gray image and deletes pixel clouds that can be excluded as marker elements; and - an identification unit which determines the color of the pixel clouds confirmed as marker elements in the gray image in the digitally stored color image.

object of the invention

It is therefore the object of the present invention to provide a tracking system and an optical measurement system for determining at least one spatial position and orientation of at least one measurement object, which at least largely avoid the disadvantages of known devices and methods. In particular, at least one spatial position and orientation of at least one measurement object should be determined with low production costs, high accuracy and less complexity.

Disclosure of Invention

This problem is solved by an optical measuring system with the features of the independent patent claim. Preferred configurations, which can be realized individually or in combination, are presented in the dependent claims.

In the following, the terms "have", "have", "comprise" or "include" or any grammatical deviations thereof are used in a non-exclusive manner. Accordingly, these terms can refer both to situations in which, apart from the feature introduced by these terms, no further features are present, or to situations in which one or more further features are present. For example, the phrase "A has B," "A has B," "A includes B," or "A includes B" can both refer to the situation in which, apart from B, there is no other element in A ( ie to a situation in which A consists exclusively of B) as well as to the situation in which, in addition to B, there are one or more other elements in A, e.g. element C, elements C and D or even further elements.

Furthermore, it is pointed out that the terms "at least one" and "one or more" as well as grammatical variations of these terms or similar terms when used in connection with one or more elements or features and are intended to express that the element or feature is simple or can be provided several times, are usually only used once, for example when the feature or element is introduced for the first time. If the feature or element is subsequently mentioned again, the corresponding term “at least one” or “one or more” is usually no longer used, without restricting the possibility that the feature or element can be provided once or more than once.

Furthermore, the terms “preferably”, “particularly”, “for example” or similar terms are used below in connection with optional features, without alternative embodiments being restricted thereby. Thus, features introduced by these terms are optional features and are not intended to limit the scope of the claims, and in particular the independent claims, by these features. Thus, as will be appreciated by those skilled in the art, the invention may be practiced using other configurations. Similarly, features introduced by "in an embodiment of the invention" or by "in an exemplary embodiment of the invention" are understood as optional features without intending to limit alternative configurations or the scope of the independent claims. Furthermore, through these introductory expressions, all possibilities to combine the features introduced here with other features, be they optional or non-optional features, remain untouched.

In a first aspect of the present description, a tracking system for determining at least one spatial position and orientation of at least one measurement object is proposed.

In the context of the present invention, a “system” can be understood to mean a device which comprises at least two elements, in particular a plurality of elements. The elements of the system can be reversible or permanently connected to each other. In particular, the elements of the system can interact. A tracking system can be understood as a device that is set up to determine, in particular to track, a spatial position and orientation of the measurement object. The tracking system can be set up to track the measurement object. "Tracking" can be understood as following a movement of the measurement object at different points in time.

The spatial position and the orientation can be determined in a coordinate system, for example in a Cartesian coordinate system or in a spherical coordinate system. Other coordinate systems are also conceivable. An origin or zero point of the coordinate system can be in a point of the device. A spatial position can be understood as a three-dimensional point (X, Y, Z) in the coordinate system, in particular a position of the measurement object. An orientation can be understood as an alignment of the measurement object, in particular a rotation in the measurement volume. The orientation can be specified by at least three angles, for example Euler angles or pitch angles, roll angles and yaw angles.

Within the scope of the present invention, a measurement object can be understood as an object of any shape that is to be measured, in particular to be tracked. The measurement object is a 3D measuring device, for example a hand-held scanner or a hand-held probe, with which a component can be scanned. For example, the 3D measuring device can be a hand-held scanner, for example a hand-held scanner available under T-SCAN from ZEISS. For example, the 3D measuring device can be a probe, for example a probe available under T-POINT from ZEISS. Alternatively, embodiments are conceivable in which the measurement object itself can be completely passive.

The measurement object, in particular the 3D measuring device, has a number of markers. The measurement object can have at least three markers. The measurement object can have four, five, six or more than ten markers, for example 35 markers or more. The markers can be in the form of active markers which are set up to emit a light beam. The measurement object, in particular the 3D measuring device, has at least one lighting device which is set up to generate the plurality of markers on a surface of the measurement object. The lighting device can have at least one light source. Each marker can have an illumination device, for example at least one LED. The markers can emit a light beam continuously or discontinuously. For example, the markers can be set up to emit the light beam at a predeterminable or predetermined frequency. The lighting device can have a modulation device which is set up to provide the light beam generated by the light source with at least one modulation frequency. The light rays emitted by the markers have different wavelengths. In particular, the emitted light rays can have wavelengths in the near infrared range. It can thus be made possible that the human eye is not irritated by visible flashes of light. Alternatively or additionally the measurement object, in particular the 3D measuring device, have retroreflectors or other markers, for example at least three retroreflectors. The measurement object can be illuminated by an external light source, for example a light source of the tracker. A retroreflector can be understood as a device which reflects an incident light beam. For example, the retroreflector can be a marker. For example, the retroreflector can be selected from the group consisting of: a cat's eye, ball lenses with a reflective layer, a marker described in U.S. 2011/0007326 A1 , U.S. 2013/0050410 A1 or US 2017/0258531 A1 , a cube prism, a cornercube. The retroreflectors can be fixed and/or exchangeable on the measurement object. A position of the retroreflectors on the measurement object can be known. The measurement object can have a large number of retroreflectors, in particular more than three retroreflectors, for example four, five, six or more retroreflectors.

The tracking system can be set up to precisely track a measurement object with markers of different wavelengths. The tracking system can be set up to carry out color multiplexing. “Color multiplexing” can be understood as tracking a measurement object in which the measurement object has markers that emit light in different wavelengths.

The tracking system can be set up to track several measurement objects in parallel. For example, each of the measurement objects can have markers with only one wavelength, with the wavelengths of the measurement objects being different. The measurement objects are then distinguished by the color of the markers. So e.g. B. two scanners and / or buttons can be used simultaneously.

A “lighting device” can be understood to mean a device that is set up to generate a light beam. In the context of the present invention, “light” can be understood to mean electromagnetic radiation in at least one spectral range selected from the visible spectral range, the ultraviolet spectral range and the infrared spectral range. The term visible spectral range basically covers a range from 380 nm to 780 nm. The term infrared (IR) spectral range basically covers a range from 780 nm to 1000 µm, with the range from 780 nm to 1.4 µm being referred to as near infrared (NIR), and the range from 15 µm to 1000 µm is called far infrared (FIR). The term ultraviolet basically encompasses a spectral range from 100 nm to 380 nm. IR light, ie light from the infrared spectral range, is preferably used within the scope of the present invention. In principle, the term “light beam” can be understood to mean a quantity of light which is emitted and/or sent out in a specific direction.

The tracking system includes at least three cameras. The cameras are each arranged at different spatial positions. The cameras each have at least two color subsystems. The color subsystems each have at least one bandpass filter. The bandpass filters of the color subsystems of the respective camera each have different passbands.

The tracking system includes at least three cameras. The cameras can include line cameras and/or area cameras, for example. A “line camera” can be understood to mean a camera which has a light-sensitive line, in particular a line sensor. For example, the line cameras can each have a plurality of pixels which are arranged in a line. The line cameras can have CCD sensors or CMOS sensors, for example. The tracking system can have a plurality of line cameras, for example three, four, five, six, seven, eight or more than ten line cameras. A cost-effective production of the tracking system can be made possible by using inexpensive line scan cameras. By using at least three line scan cameras, it is possible to increase the accuracy and robustness of the determination of the position and orientation of the measurement object, with the tracking frequency otherwise remaining the same.

The cameras are each arranged at different spatial positions. For example, the cameras can be arranged at a fixed distance from one another. By positioning the cameras at different spatial positions, the 3D coordinates of the markers can be determined by triangulation. The orientation of the measurement object can be determined from the position of the markers. The arrangement of the markers relative to each other can be specified and/or already known and/or predetermined, for example calibrated. Using more than three cameras can result in an overdetermined system of equations when calculating the 3D coordinates of the markers, which can be solved using compensation methods including optional weighting. Balancing methods and methods for weighting are known to those skilled in the art. For example, with N cameras, a noise floor decreases proportionally to the coefficient of variation 1/√N. Due to the overdetermination or redundancy, hidden or non-decodable markers in individual cameras can still be identified using Triangu lation are evaluated. The cameras can be arranged in one plane. The cameras can be rotated relative to one another in relation to an optical axis of the tracking system. The cameras can be arranged at any angle relative to one another around the optical axis. For example, the cameras can be arranged at equal intervals in a full circle around the optical axis. For example, when using line cameras, the tracking system can have two horizontal cameras whose light-sensitive line is aligned essentially horizontally. Substantially horizontally can be understood to mean a horizontal orientation, with deviations of less than 5°, preferably less than 2° and particularly preferably less than 1° from a horizontal line being possible. When line cameras are used, the tracking system can have two vertical cameras, for example, whose light-sensitive line is aligned essentially vertically. Substantially perpendicular can be understood as meaning a perpendicular orientation, deviations of less than 5°, preferably less than 2° and particularly preferably less than 1° from a perpendicular being possible. For example, the tracking system can have at least two measuring arms, with a first, horizontal measuring arm having the horizontal line cameras and a second, vertical measuring arm having the vertical line cameras. The tracking system can have further line cameras, in particular in addition to the horizontal and vertical line cameras. For example, the tracking system can have a plurality of line cameras, for example eight line cameras. The tracking system can, for example, have an annular surface on which the cameras are arranged at equal or different distances in a circle around a common circle center. However, other configurations are also conceivable. In such arrangements, a bias can be avoided by preferring a specific spatial direction.

The cameras each have at least two color subsystems. For example, each camera can have at least three, four or more color subsystems, each with a bandpass filter with a different transmission range. A "color subsystem" can be understood to mean an area, for example a partial area, or a part of the camera, which is sensitive to a specific wavelength or a specific wavelength range. A camera can also consist entirely of just one color subsystem. For example, a color subsystem can include a number of pixels of the respective camera. The different color subsystems of a camera can have the same or different numbers of pixels. Each color subsystem has at least one bandpass filter. A bandpass filter can be understood to mean a filter which only lets through light of a specific wavelength range, the so-called transmission range. The bandpass filter can be set up to suppress, in particular to block or at least attenuate, wavelengths outside the passband. The bandpass filters of the color subsystems of the respective camera each have different passbands. The cameras can each have subsystems that work in different wavelength ranges. For example, each camera can have at least a first color subsystem and at least a second color subsystem, the bandpass filter of the first color subsystem being set up to let through light of a first wavelength and the bandpass filter of the second color subsystem being set up to let light of a second wavelength Pass wavelength, wherein the first and second wavelength are different. The bandpass filters may have a passband in the near-infrared range. For example, the first and second wavelengths may be near-infrared wavelengths.

The color subsystems can each be set up to generate at least one measurement signal in response to an illumination of the respective color subsystem through at least one light beam that is let through by the respective bandpass filter and propagates from the measurement object to the tracking system. A "measurement signal" can be understood as an electronic signal. The measurement signal can depend on the incident intensity. The measurement signal can be an electrical current and/or an electrical voltage, for example. The measurement signal can be a continuous or discontinuous signal. Furthermore, the measurement signal can be an analog signal or a digital signal. The color subsystems of a camera can generate the at least one measurement signal independently of one another. The color subsystems of the respective camera can be set up to generate measurement signals in parallel, in particular simultaneously or with a time overlap.

The tracking system has at least one evaluation unit which is set up to evaluate the measurement signals of the color subsystems in parallel and to determine the position and orientation of the measurement object. An “evaluation unit” can generally be understood to mean an electronic device that is set up to evaluate measurement signals generated by the color subsystems. For example, one or more electronic connections between the color subsystems and the evaluation unit can be provided for this purpose. The evaluation unit can, for example, have at least one data processor include processing device, for example at least one computer or microcontroller. The data processing device can have one or more volatile and/or non-volatile data memories, it being possible for the data processing device to be set up in terms of programming, for example, to control the color subsystems. The evaluation unit can also include at least one interface, for example an electronic interface and/or a man-machine interface such as an input/output device such as a display and/or a keyboard. The evaluation unit can, for example, be constructed centrally or else decentrally. Other configurations are also conceivable. The evaluation unit can have at least one A/D converter. The tracking system can be set up to carry out a multiplexing method for evaluating the measurement signals. The evaluation unit can be set up to process the measurement signals generated independently and in parallel by the color subsystems and to combine information from them. Parallel evaluation can be possible by using a multiplexing method. The evaluation unit can be set up to determine 3D coordinates of the markers by means of triangulation.

Each of the color subsystems of the respective camera can have at least one lens. The optics of two color subsystems of the respective camera can be configured identically or differently. The color subsystems can have identical optics, in particular inexpensive standard optics. “Optics” can be understood to mean any optical elements, in particular at least one lens and/or at least one lens system. The color subsystems can essentially cover the same measurement volume. The color subsystems can essentially cover identical measurement volumes, with deviations from an identical measurement volume being possible as long as there is a sufficient intersection of the measurement volumes. A deviation from an identical measurement volume can, for example, be caused by the technical equipment. A “measurement volume” can be understood as a volume in which the position and orientation of the measurement object can be determined. A tracking frequency of the tracking system can correspond to a readout frequency. A color subsystem can be set up in each case to record at least one marker in a single image recording. If three color subsystems are used, for example, three markers with three different wavelengths can be recorded in parallel. A "tracking frequency" can be understood as how quickly repetitions, i.e. identical single image recordings, i.e. single image recordings with identical markers, follow one another in a periodic process. In this case, a period can have as many individual image recordings until each of the markers has been recorded. For example, the line scan cameras can be read at a frequency of 2.8 kHz. With known tracking methods (e.g. 1-out-of-n code), the tracking frequency decreases in proportion to the number of markers. For example, when using a measurement object with, for example, 35 markers, which are recorded one after the other, the tracking frequency in known tracking methods can be only 80 Hz. The present invention makes it possible, through the parallel measurement and evaluation of markers of different wavelengths, for a tracking frequency to be multiplied in proportion to the number of color subsystems. The color multiplexing according to the invention can enable markers with different wavelengths to be recorded in parallel, since markers of different wavelengths can be active at the same time without influencing one another. When using markers with, for example, three different wavelengths, it is possible to record three markers in parallel and triple the tracking frequency. The color subsystems can also be set up to simultaneously record a number of markers per color channel and thus further increase a tracking frequency.

A higher tracking frequency can significantly reduce an interpolation error between two periods, so-called frames. The color subsystems can each have different, in particular their own, optics. Each color subsystem can define its own measurement volume. Depending on requirements, a total measurement volume can be enlarged both in the direction of an end of the measurement volume close to the tracking system, so-called near end, and in the direction of a far end of the measurement volume, so-called far end. Furthermore, smaller measuring volumes can be defined in this way, so that it is possible to reduce hardware requirements for the optics as well as development and manufacturing costs. The color subsystems can preferably each have standard optics. In this way, it is possible to avoid installing demanding zoom lenses. Zoom lenses can be expensive to manufacture and difficult to calibrate because of the moving parts. The evaluation unit is set up to consolidate measurement results using linear combinations in the areas in which the measurement volumes of the color subsystems overlap.

The brightness and size of the markers of the 3D measuring device can be adapted, for example a priori, to the respective measuring field defined by the measuring volumes. Below a size of the marker a size of the light-emitting area can be understood. A brightness of the marker can be understood as meaning an intensity. For example, the tracking system can have cameras with three color subsystems each, for example a first, a second and a third color subsystem. The first color subsystems can be sensitive to light from markers with a first wavelength. The second color subsystems can be sensitive to light from markers with a second wavelength. The third color subsystems can be sensitive to light from markers with a third wavelength. The first color subsystems can define a first measurement volume in a first vicinity. The second color subsystems can define a second measurement volume in a central, more remote area than the first measurement volume. The third color subsystems can define a third measurement volume in a remote area that is further away than the second measurement volume. The measurement volumes can at least partially overlap. The first wavelength markers may have a first brightness and first size. The second wavelength markers may have a second brightness and second size. In particular, the markers with the second wavelength can be brighter and/or larger than the markers with the first wavelength. The third wavelength markers may have a third brightness and third size. In particular, the markers with the third wavelength can be brighter and/or larger than the markers with the second wavelength.

The tracking system can have at least one area camera. The tracking system can have a plurality of area cameras, for example two, three, four or more area cameras. The area cameras can each include at least one sensor, which has a matrix of pixels. Additional area cameras can be used to obtain further information about the environment and/or the measurement object. Area cameras can also use additional tracking methods such as model-based tracking, for example as in Wuest, Harald; Vial, Florence; Stricker, Didier: Adaptive Line Tracking with Multiple Hypotheses for Augmented Reality In: Institute of Electrical and Electronics Engineers (IEEE): ISMAR 2005: Proceedings of the Fourth IEEE and ACM International Symposium on Mixed and Augmented Reality. Los Alamitos, Calif.: IEEE Computer Society, 2005, pp. 62-69, US 2007/182739 A , US 2010/239121 A or in US 2012/120199 A described, and/or allow passive markers. The line cameras and the area cameras can be independent, decoupled subsystems of the tracking system. The line scan cameras and the area scan cameras can track with different frequencies and interference signals, which can be mutually compensated with sensor fusion. Sensor fusion can be understood as a merging and/or linking of data from the different cameras. This enables more accurate, robust and richer data acquisition as well as simultaneous tracking with active and passive markers. In particular, an increase in accuracy, robustness and/or speed can be achieved via sensor fusion.

In a further aspect, an optical measuring system is proposed. The optical measuring system comprises at least one tracking system according to the invention according to one of the embodiments described above or below and at least one 3D measuring device. The 3D measuring device is set up to determine 3D coordinates of an object to be measured. An object to be measured can be understood to mean any object to be measured, in particular a component or workpiece. For details and embodiments relating to the measurement system, reference is made to the description of the tracking system according to the invention.

• Ausführungsform 1: Trackingsystem zur Bestimmung von mindestens einer räumlichen Position und Orientierung mindestens eines Messobjekts, wobei das Trackingsystem mindestens drei Kameras umfasst, wobei die Kameras jeweils an verschiedenen räumlichen Positionen angeordnet sind, wobei die Kameras jeweils mindestens zwei Farb-Subsysteme aufweisen, wobei die Farb-Subsysteme jeweils mindestens einen Bandpassfilter aufweisen, wobei die Bandpassfilter der Farb-Subsysteme der jeweiligen Kamera jeweils verschiedene Durchlassbereiche aufweisen.

In summary, the following embodiments are particularly preferred within the scope of the present invention:

• Embodiment 1: tracking system for determining at least one spatial position and orientation of at least one measurement object, the tracking system comprising at least three cameras, the cameras each being arranged at different spatial positions, the cameras each having at least two color subsystems, the color -Subsystems each have at least one bandpass filter, the bandpass filters of the color subsystems of the respective camera each having different transmission ranges.

Embodiment 2 tracking system according to the previous embodiment, wherein the cameras include line cameras and/or area cameras.

Embodiment 3: Tracking system according to one of the preceding embodiments, wherein the color subsystems are each set up to, in response to an illumination of the respective color subsystem through at least one light beam passed by the respective bandpass filter and propagating from the measurement object to the tracking system, at least one To generate measurement signal, wherein the color subsystems of each camera are set up to generate measurement signals in parallel, wherein the tracking system has at least one evaluation unit, which a is aimed at evaluating the measurement signals of the color subsystems in parallel and determining the position and orientation of the measurement object.

Embodiment 4 tracking system according to one of the preceding embodiments, wherein the tracking system is set up to carry out a multiplexing method for evaluating the measurement signals.

Embodiment 5: Tracking system according to one of the preceding embodiments, wherein each camera has at least a first color subsystem and at least a second color subsystem, the bandpass filter of the first color subsystem being set up to transmit light of a first wavelength and the bandpass filter of the second Color subsystems is set up to transmit light of a second wavelength, the first and second wavelengths being different.

Embodiment 6: Tracking system according to the previous embodiment, wherein the first and the second wavelength are wavelengths in the near infrared range.

Embodiment 7 Tracking system according to one of the preceding embodiments, each camera having at least three color subsystems, each with a bandpass filter with a different transmission range.

Embodiment 8 Tracking system according to one of the preceding embodiments, each of the color subsystems of the respective camera having at least one optic, the optics of two color subsystems of the respective camera being configured identically or differently.

Embodiment 9 Optical measuring system comprising at least one tracking system according to one of the preceding embodiments and at least one 3D measuring device, the 3D measuring device being set up to determine 3D coordinates of an object to be measured.

Embodiment 10 Optical measuring system according to the previous embodiment, wherein the 3D measuring device is selected from a scanner and a probe.

Embodiment 11: Optical measuring system according to one of the two preceding embodiments, wherein the 3D measuring device has at least one lighting device which is set up to generate a plurality of markers on a surface of the 3D measuring device, wherein at least two of the markers have different wavelengths, wherein the wavelengths are each in a passband of one of the bandpass filters.

Embodiment 12 Optical measuring system according to the preceding embodiment, wherein a brightness and/or size of the markers can be adapted to a measuring field of the respective color subsystem.

character list

Further details and features of the invention result from the following description of preferred exemplary embodiments, in particular in connection with the dependent claims. The respective features can be implemented individually or in combination with one another. The invention is not limited to the exemplary embodiments. The exemplary embodiments are shown schematically in the figures. The same reference numerals in the individual figures designate elements that are the same or have the same function or that correspond to one another in terms of their functions.

• 1A und B schematische Darstellungen von Ausführungsbeispielen eines erfindungsgemäßen Trackingsystems;
• 2A und 2B schematische Darstellungen von Ausführungsbeispielen eines erfindungsgemäßen Trackingsystems;
• 3 eine schematische Darstellung eines Ausführungsbeispiels eines erfindungsgemäßen optischen Messsystems;
• 4 eine schematische Darstellung eines weiteren Ausführungsbeispiels eines erfindungsgemäßen optischen Messsystems; und
• 5 eine schematische Darstellung eines Ausführungsbeispiels eines erfindungsgemäßen Trackingsystems.

Show in detail:

• 1A and B schematic representations of exemplary embodiments of a tracking system according to the invention;
• 2A and 2 B schematic representations of exemplary embodiments of a tracking system according to the invention;
• 3 a schematic representation of an embodiment of an optical measuring system according to the invention;
• 4 a schematic representation of a further embodiment of an optical measuring system according to the invention; and
• 5 a schematic representation of an embodiment of a tracking system according to the invention.

exemplary embodiments

1A and 1B show schematic representations of exemplary embodiments of a tracking system 110 according to the invention for determining at least one spatial position and orientation of at least one measurement object 112. The measurement object 112 is a 3D measuring device 114, for example a hand-held scanner or a hand-held probe, with which a component can be scanned. For example, the 3D measuring device 114 can be a handheld scanner, for example a handheld scanner available from T-SCAN from ZEISS. For example, the 3D measuring device 114 can be a button, for example a button available under T-POINT from ZEISS. Examples of a 3D measuring device 114 are shown in FIGS 3 until 5 shown.

The tracking system 110 includes at least three cameras 116, which in the 1A and 1B are designed as line scan cameras. For example, the cameras 116 may each have a plurality of pixels arranged in a row. The cameras 116 can have CCD sensors or CMOS sensors, for example.

A cost-effective production of the tracking system can be made possible by using inexpensive line scan cameras. The tracking system 110 can have a plurality of cameras 116, for example four, five, six, seven, eight or more than ten cameras. By using at least three cameras 116, it is possible to increase the accuracy and robustness of the determination of the position and orientation of the measurement object 112 without increasing a tracking frequency. The cameras 116 are each arranged at different spatial positions. For example, the cameras 116 can be arranged at a fixed distance from one another. The cameras 116 can be arranged in one plane.

1A shows an embodiment in which the tracking system 110 has four cameras 116, which are designed as line scan cameras. For example, the tracking system 110 can have two horizontal line cameras 118, the light-sensitive line of which is essentially aligned horizontally. The tracking system 110 can have two vertical line cameras 120, the light-sensitive line of which is aligned essentially vertically. For example, the tracking system 110 can have at least two measuring arms 122 , a first, horizontal measuring arm having the horizontal line cameras 118 and a second, vertical measuring arm having the vertical line cameras 120 .

The tracking system 110 can, as in 1B shown, in addition to the horizontal line cameras 118 and vertical line cameras 120, further cameras 116, in particular line cameras. For example, the tracking system 110 can have a plurality of cameras 116, for example eight cameras 116, in particular eight line scan cameras. The tracking system 110 can have, for example, an annular surface 124 on which the cameras 116 are arranged at equal or different distances in a circle around a common circle center. However, other configurations are also conceivable. In such arrangements, a bias can be avoided by preferring a specific spatial direction.

The tracking system 110 can have at least one holding device 126 for fastening the measuring arms 122 or the annular surface 124 .

The cameras 116 each have at least two color subsystems 128 . For example, each camera 116 can have at least three, four or more color subsystems 128, each with a bandpass filter with a different passband in each case. For example, a color subsystem 128 may include a number of pixels of each camera 116 . The different color subsystems 128 of a camera 116 can have the same or different numbers of pixels. Each color subsystem 128 includes at least one bandpass filter. The bandpass filter can be set up to suppress, in particular to block or at least attenuate, wavelengths outside the passband. The bandpass filters of the color subsystems 128 of the respective camera 116 each have different transmission ranges. The cameras 116 can each have subsystems that operate in different wavelength ranges. 2A shows a possible configuration for the embodiment of FIG 1A . The cameras 116 can each have three color subsystems 128, with the bandpass filter of the first color subsystem 130 being set up to transmit light of a first wavelength, with the bandpass filter of the second color subsystem 132 being set up to transmit light of a second wavelength, the Bandpass filter of the third color subsystem 134 is set up to transmit light of a third wavelength, the first, the second and the third wavelength being different. The bandpass filters may have a passband in the near-infrared range. For example, the first, second, and third wavelengths may be near-infrared wavelengths.

2 B shows a possible configuration for the embodiment of FIG 1B . In 2 B For example, the cameras 116 located opposite one another in the circle each have identical color subsystems 128. For example, the cameras 116 may be arranged such that the first color subsystem 130, the second color subsystem 132, and the third color subsystem 134 are arranged clockwise.

The color subsystems 128 can each be set up, in response to an illumination of the respective color subsystem 128 through at least one light beam passed by the respective bandpass filter and propagating from the measurement object 112 to the tracking system 110 to generate at least one measurement signal. The color subsystems 128 of a camera 116 can generate the at least one measurement signal independently of one another. The color subsystems 128 of the respective camera 116 can be set up to generate measurement signals in parallel, in particular simultaneously or with a time overlap.

The tracking system 110 can have at least one evaluation unit 136 which is set up to evaluate the measurement signals of the color subsystems 128 in parallel and to determine the position and orientation of the measurement object 112 . For example, one or more electronic connections between the color subsystems 128 and the evaluation unit 136 can be provided for this purpose. The evaluation unit 136 can, for example, comprise at least one data processing device, for example at least one computer or microcontroller. The data processing device can have one or more volatile and/or non-volatile data memories, it being possible for the data processing device to be set up in terms of programming, for example, to control the color subsystems 128. The evaluation unit 136 can also include at least one interface, for example an electronic interface and/or a human-machine interface such as an input/output device such as a display and/or a keyboard. The evaluation unit 136 can, for example, be constructed centrally or else decentrally. Other configurations are also conceivable. The evaluation unit 136 can have at least one A/D converter. The tracking system 110 can be set up to carry out a multiplexing method for evaluating the measurement signals. Parallel evaluation can be possible by using a multiplexing method. The evaluation unit 136 can be set up to determine 3D coordinates of markers 138 of the measurement object 112 by means of triangulation.

3 shows a schematic representation of an embodiment of an optical measurement system 140. The optical measurement system 140 includes the tracking system 110, which in 3 is shown highly schematically, and a 3D measuring device 114. The tracking system 110 can, for example, as in the 1A until 2 B shown to be configured. The 3D measuring device 114 can have a plurality of markers 142 . In 3 the 3D measuring device 114 has 15 markers 142 . The markers 142 can be in the form of active markers which are set up to emit a light beam. The 3D measuring device 114 can have at least one lighting device which is set up to generate the plurality of markers 142 on a surface of the 3D measuring device. The lighting device can have at least one light source. Each marker 142 can have an illumination device, for example at least one LED. The markers 142 can emit a light beam continuously or discontinuously. For example, the markers 142 can be set up to emit the light beam at a predeterminable or predetermined frequency. The lighting device can have a modulation device which is set up to provide the light beam generated by the light source with at least one modulation frequency. The light rays emitted by the markers 142 can have different wavelengths. in the in 3 In the embodiment shown, the markers 114 can emit light in three different wavelengths. At least one first marker 144 can be set up to emit light in a first wavelength. At least one second marker 146 may be configured to emit light at a second wavelength. At least one of the markers 148 can be set up to emit light in a third wavelength. In 3 the 3D measuring device has five first markers 144 , five second markers 146 and five third markers 148 . However, other numbers are also conceivable. The first wavelength, the second wavelength and the third wavelength can be different wavelengths in the near infrared range. It can thus be made possible that the human eye is not irritated by visible flashes of light.

Each of the color subsystems 128 of the respective camera 116 can have at least one optic. The optics of two color subsystems 128 of the respective camera 116 can be configured identically or differently. The color subsystems 128 can have identical optics, in particular inexpensive standard optics. The first color subsystem 130 can have a first measurement volume 150 . The second color subsystem 132 may include a second measurement volume 152 . The third color subsystem 134 may include a third measurement volume 154 . The first color subsystem 130, the second color subsystem 132, and the third color subsystem 134 may cover substantially equal measurement volumes. The color subsystems 128 can essentially cover identical measurement volumes 150, deviations being possible as long as there is a sufficient intersection of the measurement volumes. A deviation from an identical measurement volume can, for example, be caused by the technical equipment. A tracking frequency of the tracking system 110 can correspond to a readout frequency. A color subsystem 128 can be set up in each case to record at least one marker 142 in a single image recording. If three color subsystems 128 are used, for example, three markers 142 with three different wavelengths can be recorded in parallel. through the parallel Measuring and evaluating markers 142 of different wavelengths, a tracking frequency can be multiplied proportionally to the number of color subsystems. A higher tracking frequency can significantly reduce an interpolation error between two periods of individual recordings, so-called frames.

4 shows a further embodiment of an optical measuring system 140. The color subsystems 128 can each have different optics, in particular their own optics. Each color subsystem 128 can define its own measurement volume 150, 152, 154. 4 shows measurement volumes 150, 152 and 154 lying one behind the other and partially overlapping. Depending on requirements, a total measurement volume can be directed both in the direction of an end of the measurement volume close to the tracking system 110, so-called near end, and in the direction of a far end of the measurement volume, so-called far End, be enlarged. Furthermore, smaller measuring volumes can be defined in this way, so that it is possible to reduce hardware requirements for the optics as well as development and manufacturing costs. The color subsystems 128 can preferably each have standard optics. In this way, it is possible to avoid installing demanding zoom lenses. The evaluation unit 136 is set up to consolidate measurement results by linear combination in the areas in which the measurement volumes of the color subsystems overlap. The brightness and size of the markers 142 can be adapted, for example a priori, to the respective measurement field defined by the measurement volumes 150, 152 and 154. For example, the tracking system 110 as shown in FIGS 1A until 2 B be designed. The first color subsystems 130 can be sensitive to light from the first markers 144 . The second color subsystems 132 can be sensitive to light from second markers 146 . The third color subsystems 134 can be sensitive to light from third markers 148 . The first color subsystems 130 can define the first measurement volume 150 in a first vicinity. The second color subsystems 132 may define the second measurement volume 152 in a central, more remote area than the first measurement volume 150 . The third color subsystems 134 can define the third measurement volume 156 in a far area, which is further away than the second measurement volume 154. The measurement volumes 150, 152, 154 can at least partially overlap. The first markers 144 can have a first brightness and a first size. The second markers 146 can have a second brightness and second size. In particular, the second markers 146 can be brighter and/or larger than the first markers 144. The third markers 148 can have a third brightness and third size. In particular, the third markers 148 can be lighter and/or larger than the second markers 146.

5 12 shows an embodiment in which the tracking system 110 has two area cameras 156 . The tracking system 110 can have a plurality of area cameras 156, for example two, three, four or more area cameras 156. The area cameras 156 can each comprise at least one sensor which has a matrix of pixels. Additional area cameras 156 can be used to obtain further information about the surroundings and/or the measurement object 112 . Furthermore, area cameras 156 can allow additional tracking methods such as model-based tracking and/or passive markers. The 3D measuring device 114 can have retroreflectors 158 or other passive markers, for example at least three retroreflectors 158. The retroreflectors 158 can be fixed and/or exchangeable. A position of the retroreflectors 158 on the measurement object 112 can be known. The line cameras and the area cameras 156 can be independent, decoupled subsystems of the tracking system 110 . The line cameras and the area cameras 156 can track with different frequencies and interference signals, which can be mutually compensated with sensor fusion. This enables more accurate, robust and richer data acquisition as well as simultaneous tracking with active and passive markers. In particular, an increase in accuracy, robustness and/or speed can be achieved via sensor fusion.

Reference List

110

tracking system

112

measurement object

114

3D measuring device

116

camera

118

horizontal line scan camera

120

vertical line scan camera

122

measuring arm

124

surface

126

holding device

128

color subsystem

130

first color subsystem

132

second color subsystem

134

third color subsystem

136

evaluation unit

140

optical measuring system

142

marker

144

first marker

146

second marker

148

third marker

150

first measurement volume

152

second measurement volume

154

third measurement volume

156

area camera

158

retroreflector

Claims (8)

Optical measuring system (140) comprising at least one tracking system (110) for determining at least one spatial position and orientation of at least one 3D measuring device (114), wherein the optical measuring system (140) comprises at least one 3D measuring device (114), the tracking system (110) comprises at least three cameras (116), the cameras (116) each being arranged at different spatial positions, the cameras (116) each having at least two color subsystems (128), the color subsystems (128) each have at least one bandpass filter, the bandpass filters of the color subsystems (128) of the respective camera (116) each having different transmission ranges, the tracking system (110) having at least one evaluation unit (136) which is set up to measure the measurement signals of the color evaluate subsystems (128) in parallel and to determine the position and orientation of the measuring device (114), and wherein the evaluation unit (136) is set up i st, in the areas in which the measurement volumes of the color subsystems (128) overlap, to consolidate measurement results using linear combinations, the 3D measurement device (114) being set up to determine 3D coordinates of an object to be measured, the 3D Measuring device (114) has at least one lighting device which is set up to generate a plurality of markers (142) on a surface of the 3D measuring device (114), with at least two of the markers (142) having different wavelengths, with the wavelengths each in a passband of one of the bandpass filters, wherein a brightness and/or size of the markers (142) can be adapted to a measuring field of the respective color subsystem (128). Optical measuring system (140) according to the preceding claim, wherein the 3D measuring device (114) is selected from a scanner and a probe. Optical measuring system (140) according to one of the preceding claims, wherein the cameras (116) comprise line cameras and/or area cameras (156). Optical measuring system (140) according to one of the preceding claims, wherein the color subsystems (128) are each arranged in response to an illumination of the respective color subsystem (128) passed through at least one of the respective bandpass filter and away from the measurement object (112) to the tracking system (110) propagating light beam to generate at least one measurement signal, wherein the color subsystems (128) of the respective camera (116) are set up to generate measurement signals in parallel. Optical measurement system (140) according to one of the preceding claims, wherein each camera (116) has at least a first color subsystem (130) and at least a second color subsystem (132), the bandpass filter of the first color subsystem (130) being set up is to pass light of a first wavelength and wherein the bandpass filter of the second color subsystem (132) is arranged to pass light of a second wavelength, the first and second wavelengths being different. The optical measurement system (140) of the preceding claim, wherein the first and second wavelengths are near-infrared wavelengths. Optical measuring system (140) according to one of the preceding claims, wherein each camera (116) has at least three color subsystems (128), each with a bandpass filter with a different transmission range in each case. Optical measuring system (140) according to one of the preceding claims, wherein each of the color subsystems (138) of the respective camera (116) has at least one optic, the optics of two color subsystems (128) of the respective camera (116) being identical or different are designed.

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